FIG. 1A depicts a schematic diagram of a portion of a telecommunications system in the prior art. The depicted portion includes telecommunications network 110, which comprises: layer-0 nodes 101-1 through 101-12, layer-0 route segments 102-1 through 102-17, layer-2 nodes 103-1 through 103-3, and layer-2 bundle 104-1 through 104-2. The elements within telecommunications network 110 are interrelated as shown.
Network 110 enables devices such as user endpoints to exchange data packets with one another. In particular, network 110 constitutes a wide-area network (WAN), although it could alternatively constitute a local-area network (LAN) or other type of network. Network 110 operates on Layer-2 (L-2) Provider Backbone Bridging (PBB) technology and, having one or more Ethernet rings, can be referred to as an Ethernet transport network. The connectivity among L-2 nodes, in which an L-2 connection spanning a pair of L-2 nodes is referred to as an Ethernet bundle, are routed over underlying Layer-0 (L-0) route segments, which are optical Dense Wavelength Division Multiplexing (DWDM) segments in this case. An ITU-T G.8032 ring serves as the protection mechanism at the Ethernet layer.
Layer-0 (L-0) node 101-m, wherein m can have a value equal to 1 through 12, inclusive, is a device that interconnects two or more layer-0 route segments. Each L-0 node supports DWDM.
Layer-0 (L-0) route segment 102-n, wherein n can have a value equal to 1 through 17, inclusive, refers to the physical link or medium connecting two L-0 nodes to each other. For clarity purposes, only L-0 route 102-1 is shown, although there exists an L-0 route segment 102-n between other pairs of L-0 nodes as depicted. Each L-0 route segment supports DWDM.
Layer-2 (L-2) node 103-p, wherein p can have a value equal to 1 through 3, inclusive, is a device that provides layer-2 (i.e., data link) computer networking functionality. Each L-2 node supports the Ethernet protocol. Each L-2 node comprises an L-0 node as well. As depicted, L-2 node 103-1 comprises L-0 node 101-1, L-2 node 103-2 comprises L-0 node 101-5, and L-2 node 103-3 comprises L-0 node 101-9.
Layer-2 (L-2) bundle 104-q, wherein q can have a value equal to 1 or 2, inclusive, refers to the data link that connects two L-2 nodes to each other. As depicted, L-2 bundle 104-1 connects L-2 node 103-1 and 103-2, and L-2 bundle 104-2 connects L-2 node 103-2 and 103-3. Each L-2 bundle traverses one or more L-0 route segments between the two L-2 nodes connected by L-2 bundle 104-q. 
There are situations in which the data packet routing performed within telecommunications system 100 can be disrupted. For example, and as depicted in FIG. 1B, a physical link can be cut, as represented by cable break 105. As depicted, break 105 has disrupted the L-0 route segment between L-0 nodes 101-6 and 101-7 and, consequently, has disrupted the L-2 bundle between L-2 nodes 103-2 and 103-3. Depending on various factors, such disruptions can be frequent, and multiple disruptions can occur simultaneously with one another.
Therefore, what is needed is a technique for improving service availability that avoids at least some of the disadvantages in the prior art.